GMAT Question of the Day (July 24): Mixture Problem and Critical Reasoning

There are two bars of gold-silver alloy; one piece has 2 parts of gold to 3 parts of silver, and the other has 3 parts of gold to 7 parts of silver. If both bars are melted into a 8-kg bar with the final ratio of 5:11 (gold to silver), what was the weight of the first bar?

In a monogamous culture, 100% of the adults are married. The average number of children per family is five and over-population is a threat. Programs to encourage birth-control have been ineffective. It has been suggested that this failure is due to these programs ignoring a tradition that values male children very highly, so that every parent wants to have at least one son. It is proposed that couples be encouraged to use birth-control measures after the birth of their first son.

If this proposal is widely accepted in the culture, we may expect that:

(A) the rate of population increase will be slowed, and future generations will contain a disproportionately high number of females.
(B) the rate of population increase will be slowed, and the gender balance in future generations will remain as it is at present.
(C) the rate of population growth will remain the same, and future generations will contain a disproportionately high number of females.
(D) there will be no significant effect either on population growth or on gender balance.
(E) the population will decline precipitously, because approximately half of all families will have only a single child.